Free piston machine



J1me 1941 R. PATERAS PESICARA 2,244,215

FREE PISTON MACHINE Filed Feb N QN NNN NN MN WNW Q Q MN Q Patented June 3, 1941 one-fifth to Societe dEtudes 'et de Partici tions Eau, Gaz, Electricite, Energie S. A., Geneva, Switzerland, a society of Switzerland Application February 16, 1939, Serial No. 256,751- 1 In Luxemburg February 19, 1938 13 Claims.

The present invention relates to mechanisms for synchronizing the displacements of the'parts, moving in a reciprocating manner in'opposite directions, of a free piston machine, that isto say of a machine the pistons of which can have variable strokes.

It is known to constitute such mechanismsby connecting the reciprocating parts in question, which are to be synchronized, to the ends of oscillating levers, through the medium of simple connecting rods, said oscillating leversbeing generally disposed on either side of the machine, respectively, and being either of parallel directions or of crossed directions, as the case may be.

- But this structure produces, during theworking of the machine, inertia forces directed at right" angles to the direction of the displacements of the reciprocating parts. These inertia forces create, in the case of a machine provided with oscillating levers parallel to each other, an alternating torque which tends to produce an oscillationof the machine about a transverse axis, and, in the case of a machine the oscillating levers of which are of crossed arrangement, instantaneous torques which tend to rotate the reciprocating parts question about their axis. 7

It has been suggested, in orderto avoid this drawback, to interconnect thereciprocating parts which are to be synchronized through the medium I of kinematic systems known as lazy tongs, in

which systems the detrimental reactions compensate one another. These systems were then pivoted about a fixed axis passing through their center of symmetry, but their points of fixation to the reciprocating parts of the machine were so located that the axis of symmetry of said systems remained-constantly parallel to the axis of the machine.-

In other words, of saidreciprocating parts could take place only owing to the deformation ofthe balanced kine-' matic mechanisms; Thereioreit was necessary, with this construction, to give these balanced mechanisms relatively important dimensions, and therefore masses, which was disadvantageous the longitudinal displacements ,for the obtainment of high rates-of operation of r the machine, if it was desired to make possible normal maximum displacements of these reciproeating parts. I

The chief object of the present invention is to provide a mechanism of the type above described which is better adapted to meet the re- 7 quirements of practice than similar mechanisms made up to this time and, in particular, free from the disadvantages above set iorth.

According to the present invention, in order to reduce the volume and the mass ot'the mecha-' nism in question, it is constituted by a kinematic system which is devised insuch manner as to complywith either of the two following conditions: 7

a. The reactions normal to the pathof movement of the reciprocating parts compensate one another in the mechanism itself, atany timeiofthe operation thereof, said mechanism being then arranged to oscillate about a fixed axis;

b. 01', alternately, the reactions normal to path of travel of the reciprocating parts are transmitted to, at least one rigid element arranged in such manner as to undergo simultaneously the reactions of opposed direction, so as to balance I them on said element. 7

1 Other features of the present invention some specific embodiments thereof.

Preierred embodiments of the present invention will be hereinafter described, with reierence'to the y way or accompanying drawing, given merely example, and in which:

Fig. 1 diagrammaticallyshows, in axial secti view, a free piston machine the reciprocating parts 01', which are synchronized through a mechanism made according to a tirst embodiment oi the present invention;

Fig. 2 is a view, similar to Fix, 1, showing another embodiment, of t same kind that or v Fig.1; N a.

Fig. 3 shows, "in diagrammatic sectional 'view,

a modification of the synchronizing means or Fig. 2. a

In the following description, the inv cntion will be set iorth as applied to a tree piston machine made in any suitable conventional manner, Formstance, as shown by Fig; 1, this machine is a motor-compressor including, on the one hand, two motor pistons land- I niountedina cylinder the wall of which is 'providedwith inlet ports 3 and outlet ports 4 which-are opened, respectively by said pistons l and 1', when are moving close to' the ends of their outward strokes, and on t the other hand, compressor pistons i and i", re:- j spectiveiy rigid with said pistons l and I adapted, to coact with cylinders'provided with suction valvesi and discharge valves I,

The object of the invention is to provide a device ior synchronizing the displacements, in opposed directions, or the reciprocating parts or said v machine. I

the.

will resuit from the followin detailed descriptionot According to the present invention, I proceed as follows:

First, according to one embodiment of my invention, I interconnect the displacements of the reciprocating parts of said machine through a kinematic system which is balanced (that is to say a system in which the normal reactions of opposed directions which take place during the operation of the system destroy each other at any time) and which is pivotally connected to said reciprocating parts at points chosen in such manner that the whole of said system oscillates about a fixed axis during the operation of the machine.

With such an arrangement, it is possible to make this kinematic system of dimensions considerably smaller than those which were necessary when said system worked merely by deformation as in the prior arrangements.

This is due to the fact that the displacements of the reciprocating parts in question are made possible:

a. Partly by the oscillating movement of the whole of the balanced system, and

b. Partly by the deformation of said balanced system. i

The dimensions of said balanced system, which determine the maximum amplitude of its deformations, can therefore be chosen lower than those of a system of this kind the deformations of which would correspond to the whole of thestroke of the reciprocating parts of the machine. Then, advantageously, as it will be supposed in the following description, said balanced system is constituted by two similar elements disposed on either side of the machine. Of course, there are many possiblepractical embodiments of this system, but I have found that it is advantageous, in practice, to make use of one of the following embodiments; in which the kinematic system constitutes a lazy tongs mechanism, or an equivalent .mechanical system- According to the first of these-embodiments,- each of saidsystems is constitutedby an as sembly of, oscillating connecting rods and levers, adapted to pivot about a fixed axis 0 and constituting a lazy tongs system the ends of which are pivoted to pieces respectively rigid with each of the reciprocating parts of the machine, at points of said pieces locatedon opposite sides of the plane, parallel to the pathsof movement of said reciprocating parts, passing through axis II.

An embodiment complying withgthese conditions is shown by way of example by Fig. 1-.

The pivot axis 0 is carried by an arm 8 fixed in line with the frameof the machine.

On this pivot axis are pivoted two crossed oscillating levers 9 and 91, and the ends of these oscillating levers are connected to sliding rods I0 and I0, rigid respectively with the reciprocating parts of the machine through connecting rods forming deformable parallelograms with said oscillating levers. For instance, oscillating lever 9 is connected to sliding rods l0 and I0 through connecting rods I I and II and oscillating lever S'is connected to sliding rods l0 and Ill through connecting rods H1 and ll'1. The connecting rods corresponding to each of said sliding rods are pivoted about a common axis It or I! carried by a piece l3 or l3, rigidly fixed on the cor responding rod.

According to a second embodiment of the prescut invention, which is illustrated by Fig. 2 of the drawing, the synchronizing means are housed in the median part of the machine.

Advantageously, in this case, the fixed axis I is arranged in such manner that it projects on either side of the cylinder.

The respective inner. faces of the compressor pistons 5 and 5 carry sliding rods 10 and III the ends of which project from the corresponding compressor cylinders and are, preferably, guided at least by one slide way, for instance slideways said sliding rods being arranged in such manner that their ends occupy at any time symmetrical positions with respect to axis 0.

, The displacements of the ends of said sliding rods are combined, in such manner as to synchronize them, respectively through connecting rods II II, with those of the ends of an oscillating lever 9 adapted to oscillate about axis 0.

In order to balance the perturbing normal reactions, the mechanism further includes a second oscillating lever 91, of shorter length than oscillating lever 9, the ends of which are respectively connected to connecting rods H and II through small connecting rods II and '1, respectively, in 'such manner that oscillating levers 9 and 9', connecting rods H and ll'and connecting rods H1 and II; form symmetrical deformable parallelograms; Connecting rods H1 and '1 are pivoted to connecting rods H and II through axes l5 and I5, preferably positioned between the extreme pivoting axes of said connecting rods.

Such a mechanism, in whichthe normal reactions balance'each other at any time of its operation, can come to occupy, according as the reciprocating parts of the machine are at the outer ends of their strokes or at their inner ends, either position I shown in the usual manner on the drawing, or position ,II lustrated by solid black lines.

It should be noted that, in the first case, the stresses are transmitted wholly through oscillating lever S, while in the second case (where they are higher due to the fact that the volume of the combustion chamber is minimum) they are transmitted through oscillating lever 91, which must consequently be made, same as the corresponding connecting rods, in such manner as to be able to transmit more important stresses than said oscillating lever 9.

According to the embodiment which has just been described, the synchronizing mechanisms are pivoted to the respective ends of rods l0 and lflandsome portions of said mechanism move along paths which intersect the directions of said rods.

Now, it may be of advantage, in some cases,

lever B one ofthe ends of which is pivotally connected to one end of a connecting rod II the other end of which is pivoted to a piece 13' rigid with rod Ill. The other endof said oscillating lever 9 is pivotallyv mounted on the middle part of an oscillating lever- I6 arranged parallel to connecting rodi One, of the ends of said oscillating lever I6 is pivotally connected to a piece l3 rigidwith sliding rod I0, whereas its other end is linked to piece [3' through a connecting rod l1 parallel to oscillating lever l and diagrammatically 11-- which is pivoted to said piece l3 about the same axis as connecting rod II.

I have shown at I and II the extreme positions of such a mechanism. In position I, the efforts are transmitted through oscillating lever l6 and connecting rod I1, and, in position II, they are transmitted through oscillating lever 9, connecting rod l I and one half of oscillating lever 16.

It should be noted that, advantageously, in all the cases which have been above mentioned and when the free piston machine is fed through an injection pump, said pump should be connected to those of the elements of the synchronization mechanism the velocity of which is higher when the parts are close to the inner end of the piston stroke.

The solution above described permits of eliminating the perturbing reactions on the inside of the moving parts of the synchronizing mechanism of the machine.

In all cases, whatever be the particular embodiment that is chosen, the operation and advantages of the synchronizing device according to the invention results suificiently clearly from the above description for making it unnecessary to enter into further explanations.

Of course, while the devices above described permit of wholly eliminating the normal reactions of the reciprocating parts of the machine, the invention also applies to the cases in which these reactions are merely considerably reduced, in particular close to the extreme outer positions of the pistons, where the inertia stresses are maximum.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and efficient embodiments of the present invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition, and form of the parts without departing from the principle of the present invention as comprehended within the scope of the appended claims.

What I claim is:

1. In a machine including a frame and two parts reciprocating in opposed directions along a common longitudinal axis of movement with respect to said frame, a synchronizing device which comprises, in combination, two members, each rigid with one of said parts, located on opposite sides of said longitudinal axis and at distances therefrom, and lazy tong interconnecting means interposed between said two members, pivoted at each end to one of said members and having at least one central oscillating lever pivoted to said frame about an axis perpendicular to said longitudinal axis and intersecting it.

2. In a machine including a frame and two parts reciprocating in opposed directions along a common longitudinal axis of movement with respect to said frame, a synchronizing device which comprises, in combination, two members, each rigid with one of said parts, respectively, located on opposite sides of said longitudinal axis and at distances therefrom, respectively, and lazy tong interconnecting means interposed between said two members, pivoted at each end to one of said members and including two central levers pivoted to each other and to said frame, at their middle points, about an axis at right angles to said longitudinal axis and intersecting it.

3. In a machine including parts reciprocating in opposed directions a frame and two along a common longitudinal axis of movement with respect to said frame, a synchronizing device which comprises, in combination, two rods, slidable with respect to said frame and parallel to said longitudinal axis, each rigid with one of said reciprocating parts, located on opposite sides of said longitudinal axis and at distances therefrom, and lazy tong interconnecting means interposed between said two rods, pivoted-at each end to one of said sliding rods and including at least one central oscillating lever pivoted to said frame about an axis perpendicular to said longitudinal axis and intersecting it.

4. In a machine including a frame and two parts reciprocating in opposed directions along a common longitudinal axis of movement with respect to said frame. a synchronizing device which comprises, in combination, two rods slidable with respect to said frame and parallel to said longitudinal axis each rigid with one of said reciprocating parts, located on opposite sides of said longitudinal axis and at distances therefrom, and lazy tong interconnecting means interposed between said two rods, pivoted at each end to one of said sliding rods and including at least one central oscillating lever pivoted to said frame about an axis perpendicular to said longitudinal axis and intersecting it at a point thereof located outside of the interval' between said two reciprocating parts.

5. In a machine including a frame and two parts reciprocating in opposed directions along a common longitudinal axis of movement with respect to said frame, a synchronizing device which comprises, in combination, two rods slidable with respect to said frame and parallel to said longitudinal axis each rigid with one of said reciprocating parts, located on opposite sides of said longitudinal axis and at distances therefrom, respectively, and lazy tongs interconnecting'means interposed between said two rods, pivoted at each end to one of said sliding rods and including at least one central oscillating lever pivoted to said frame about an axis perpendicular to said longitudinal axis andintersecting it at a point thereof located between said two reciprocating parts.

6. In a machine including a frame and two parts reciprocating in opposed directions along a common longitudinal axis of movement with respect to said frame, a synchronizing device which comprises, in combination, two rods, slidable with respect to said frame and parallel to said longitudinal axis, each rigid with one of said reciprocating parts, located on opposite sides of said longitudinal axis and at distances therefrom, respectively, and lazy tong interconnecting lmeans interposed between said two rods, consisting of two central oscillating levers and two pairs of connecting rods pivoted to one another so as to form two deformable parallelograms having a common apex at the middle points of said oscillating levers, where they are pivoted to each other and to said frame about an axis at right angles to said longitudinal axis and intersecting it, the opposed apexes of said parallellograms, respectively, being pivoted to said rods.

7. In a machine including a frame and two parts reciprocating in opposed directions along a common longitudinal axis of movement with respect to said frame, a synchronizing device which comprises, in combination, two rods, slidable with respect to said frame and parallel to said longitudinal axis, each rigid with one of said reciprocating parts, located on opposite sides of said longitudinal axis and at distances therefrom, respectively, and lazy tong interconnecting means interposed between said two rods, consisting of two central oscillating levers and two pairs of connecting rods pivoted to one another so as to form two deformable parallellograms having a common apex at the middle points of said oscillating levers, where they are pivoted to each other and to said frame about an axis at right angles to said longitudinal axis and intersecting it at a point thereof located outside of the interval between said two reciprocating parts, the opposed apexes of said parallellograms, where said connecting rods are respectively pivoted to each other, being located on said rods.

8. In a machine including a frame and two parts reciprocating in opposed directions along a common longitudinal axis of movement with respect to said frame, a synchronizing device which comprises, in combination, two rods slidable with respect to said frame and parallel to said longitudinal axis, each rigid with one of said reciprocating parts, located on opposite sides of said longitudinal axis and at distances therefrom, respectively, and lazy tong interconnecting means interposed between said two rods, consisting of two central oscillating levers pivoted to each other and to said frame about an axis at right angles to said longitudinal axis and intersecting it, two connecting rods interposed between the ends of one of said levers, respectively, and said respective rods and parallel to the other lever, and two other connecting rods, interposed between the ends of the second lever, respectively and intermediate points of said first mentioned connecting rods, so as to be constantly parallel to the first mentioned lever.

9. In a machine including a frame and two parts reciprocating in opposed directions along a common longitudinal axis of movement with respect to said frame, a synchronizing device which comprises, in combination, two rods slidable with respect to said frame and parallel to said longitudinal axis, each rigid with one of said reciprocating parts, respectively, located on opposite sides of said longitudinal axis and at distances therefrom, respectively, and lazy tong interconnecting means interposed between said two rods, consisting of two central oscillating levers pivoted to each other and to said frame about an axis at rightangles to said longitudinal axis and intersecting-.itat a point thereof located between said two reciprocating parts, two connecting rods interposed between the ends of said levers, respectively, and said respective rods and parallel to the other lever, and two other connecting rods, interposed between the ends of the second lever, respectively, and intermediate points of said first mentioned connecting rods, so as to be constantly parallel to the first mentioned lever.

10. In a machine including a frame and two parts reciprocating in opposed directions along a common longitudinal axis of movement with respect to said frame, a synchronizing device which comprises, in combination, two rods, slidable with respect to said frame and parallel to said longitudinal axis, each rigid with one of said reciprocating parts, located on opposite sides of said longitudinal axis and at distances therefrom, respectively, and interconnecting lever means interposed between said two rods, including an oscillating lever pivoted to said frame about an axis perpendicular to said longitudinal axis and intersecting it, a second lever pivoted at its middle point to one end of said first mentioned lever and at one of its ends to one of said sliding rods, a connecting rod interposed between the other end of said first mentioned lever and the other sliding rod and parallel to said second mentioned lever, and a connecting rod pivoted at one end to said first mentioned connecting rod about the axis of oscillation thereof with respect to said second mentioned sliding rod and at the other end to the second end of said second mentioned lever, said second mentioned connecting rod being parallel to said first mentioned lever.

11. In a machine including a frame and two parts reciprocating in opposed directions along a common longitudinal axis of movement with respect to said frame, a synchronizing device which comprises, in combination, two members,

each rigid with one of said parts, located on opposite sides of said longitudinal axis and at distances therefrom, and interconnecting lever means interposed between said two members, pivoted at each end to one of said members and having at least one central oscillating lever pivoted to said frame about an axis perpendicular to said longitudinal axis and intersecting it.

12. In a machine including a frame and two parts reciprocating in opposed directions along a common longitudinal axis of movement with respect to said frame, a synchronizing device which comprises, in combination, two rods, slidable with respect to said frame and parallel to said longitudinal axis, each rigid with one of said reciprocating parts, located on opposite sides of said longitudinal axis and at distances therefrom, and interconnecting lever means interposed between said two rods, pivoted at each end to one of said sliding rods and including at least one central oscillating lever pivoted to said frame about an axis perpendicular to said longitudinal axis and intersecting it.

13. In a machine including a frame and two parts reciprocating in opposed directions along a common longitudinal axis of movement with respect to said frame, a synchronizing device which comprises, in combination, two rods, slidable with respect to said frame and parallel to said longitudinal axis, each rigid with one of said reciprocating parts, located on opposite sides of said longitudinal axis and at distances therefrom, interconnecting lever means interposed between said two rods, pivoted at each end to one of said sliding rods and including at least one central oscillating lever pivoted to said frame about an axis perpendicular to said longitudinal axis and intersecting it, and links pivoted to said rods and to opposite ends of said lever.

RAUL PATERAS PESCARA. 

